Silica-cadmia glass batches for producing low-to-medium expansion glasses

ABSTRACT

Glass batch compositions for producing glasses having linear coefficients of thermal expansion in the range of from about 10 X 10 7 to about 20 X 10 7 in./in./* C. and which batch compositions are composed of finely divided batch materials consisting essentially of from 70-90 mole percent SiO2, up 1 to 15 mole percent CdO, and the balance of such Composition, if any, being finely divided batch materials composed essentially of one or more oxides selected from the group consisting of Al2O3, TiO2, B2O3, CuO, MnO, ZnO, ZrO2, Sb2O3, AlF3 and P2O5.

Waite State atemlt Baalr 15] 3,@S,7SI1

[451 Mar. 21, 11972 [54] SlLliCA-CADMIA GLASS BATCHES FUR PRODUCINGLUW-TU-MEDIUM [73] Assignee: Owens-Illinois,lne.

[22] Filed: Aug. 28, 1969 [21] Appl.No.: 853,960

Related U.S. Application Data [63] Continuation-impart of Ser. No.465,741, June 21,

[52] 11.8. CI ..106/52,106/54 [51] Int. Cl ...C03c 3/04 [58] Field ofSearch ..106/52, 54

[56] References Cited UNITED STATES P ATENTS 2,326,059 8/1943 Nordberg..106/52 3,275,492 9/1966 Herbert ....l06/54 1,526,423 2/1925 Keyes106/54 1,676,331 7/1928 Hochstein ..106/54 3,326,703 6/1967 Harrington..106/54 OTHER PUBLICATIONS lmaoka et al., Advances In Glass Technology-Plenum Press (1962) Glass-Formation Range and Glass Structure" pp. 149-155 TP845T52 Searle-Refractory MaterialsChas. Griffin & Co., London(1950), pp. 94- 96; 184-185, TN67754 Levin et al.-Phase Diagrams ForCeramists-Amer. Ceramic Soc., Ohio, 1964, pp. 260- 262 PrimaryExaminer-Tobias E. Levow Assistant Examiner-W. R. SatterfieldAttorney-Richard B. Dence and E. J. Holler 5 7] ABSTRACT Glass batchcompositions for producing glasses having linear coefficients of thermalexpansion in the range of from about 10 X 10 to about 20 X 10" in./in./C. and which batch compositions are composed of finely divided batchmaterials consisting essentially of from 70-90 mole percent SiO up 1 to15 mole percent Cd(), and the balance of such Composition, if any, beingfinely divided batch materials composed essentially of one or moreoxides selected from the group consisting of A1 0 TiO B 0 CuO, MnO, ZnO,ZrO Sb O MP and 24 Claims, No Drawings SlLlCA-CADMIA GLASS BATCHES FORPRODUCING LOW-TO-M-EDIUM EXPANSION GLASSES The present invention is acontinuation-in-part of copending application Ser. No. 465,741, filedJune 21, 1965, now abandoned, and relates in general to glass batchcompositions for producing glasses possessing low-to-medium coefiicientsof thermal expansion and having desirable melting temperatures, and moreparticularly to glass batch compositions for producing glasses based onsilica and cadmium oxide by generally conventional glass batch meltingprocedures.

In the art of glass making, certain glasses are known that have goodthermal expansion characteristics in the low-tomedium expansion rangecorresponding to a range of coefficients of linear expansion of from 10X 10- to 20 X 10*in ./in./ C. in the temperature range of from to 300C.. However, problems have arisen in connection with using these glassesbecause of the difficulty in melting glass batch compositions productiveof such glasses without resort to excessively high batch meltingtemperatures or resort to expensive and complicated processingtechniques such as vapor phase reactions in which productioncapabilities are so extremely limited and processing costs so high thatsuch glasses have long been conventionally regarded as being outside therealm of practicability for commercial production of moderate costglasses. In consequence, the practical applications of these glasses hasbeen severely limited.

Therefore, it is an object of the present invention to providelow-to-medium expansion glasses which contain both silica and cadmiumoxide and which are capable of being prepared directly from finelycomminuted glass making batch materials in accordance with generallyconventional glass batch melting procedures, and thus making suchglasses available for a wide variety of uses heretofore considered to beeconomically impracticable.

lt is a further object of the present invention to provide glass batchcompositions for producing glasses possessing low-tomedium expansionproperties and for producing such glasses from glass batch compositionsat relatively low melting temperatures.

In attaining the above objectives, it is to be appreciated that oneparticularly significant feature of the present invention resides inproviding glass batch compositions based on silica and cadmium oxidewhich at relatively low melting temperatures are productive of glasseshaving low-to-medium thermal expansion properties.

Another important feature of the present invention resides in providingglass batch compositions containing from about 70 to 90 mole percentsilica, from 1 to 15 mole percent cadmium, and the remaining content ofup to about 20 mole percent comprised of one or more additives, at whichrelatively low melting temperatures are suitable for producing glasseshaving low-to-medium thermal expansion properties.

A further feature of the present invention resides in the provision ofrelatively low melting temperature glass batch compositions forproducing glasses comprising the SiO -CdO- Al o -TiO system andaccommodating one or more other selected, compatible oxides asadditives.

A further salient feature of the present invention resides in theprovision of relatively low melting temperature glass batch compositionsfor producing glasses comprising the SiO -CdO- TiO system andaccommodating one or more compatible glass batch additives.

Other objects, features and advantages of the present invention willbecome readily apparent to those ordinarily skilled in the art from thefollowing detailed description thereof.

In accordance with certain of the broader aspects of the presentinvention, finely divided glass batch compositions are provided whichare readily capable of being melted at relative- 1y low meltingtemperatures to produce glasses predominantly composed of silica andcadmium oxide and which possess coefficients of thermal expansiongenerally within the low-tomedium range of about to about 20 Xl0in./in./ C. over the temperature range of from 0 to 300 C. In a moreparticular aspect, the glass batch compositions of the present inventioncomprise about 70-90 mole percent of finely divided silica together withup to about 15 mole percent of finely divided cadmium oxide and from0-20 mole percent of finely divided compatible glass batch components.

The glass batch compositions of the present invention, in a furtherparticular aspect, consist essentially of about 70-90 mole percentsilica, up to about 15 mole percent cadmium oxide, and any balance beingcomposed of one or more batch constituents such as titanium dioxide,boric oxide, aluminum trioxide, copper oxide, zinc oxide and manganeseoxide; a source of boron and/or aluminum always being present to provideat least one mole percent of B 0 or A1 0 in the final glass.

For purposes of further modification, the glass batch compositions ofthe present invention may also contain selected amounts of othercompatible glass batch constituents to an extent generally not exceedingabout 20 mole percent. Representative of preferred compatibleconstituents are zirconium dioxide, aluminum fluoride and antimonytrioxide, as well as other conventional glass batch constituents whichdo not tend to adversely affect the nature of the glass.

Included in the glass batch compositions of the present invention arethose containing at least three of the following components, in molepercent, based on the total batch composition:

Component Mole Percent SiO, 70 to CdO up to l5 Al,0 0 to 15 TiO, 0 to 108,0, 0 to 10 Copper Oxide 0 to 10 MnO 0 to 10 ZnO 0 to 10 Preferredcompositions coming within the scope of the compositions set forth aboveare, as follows:

Component Mole Percent SiO, 70 to 90 CdO l to l5 Alp, 3 to I0 TiO, 0 toI0 5,0, 0 m I0 Copper Oxide 0 to I0 MnO 0 to 10 ZnO 0 to 10 Still otherpreferred compositions that come within the formulation set forth aboveare shown below, in mole percent:

Component Mole Percent SiO, 70 to 90 CdO l to 15 ALO, 3 to l0 TiO: 5 to10 5,0,, 0 to 10 CuO 0 to 10 MnO 0 to I0 2110 0 to H) In another aspectof the invention, the glasses of the present invention include thoseprepared from the following glass batch compositions in mole percent:

Component Mole Percent SiO, 70 to 90 CdO up to 15 A1 0, 0 to 15 TiO, 0to ID 3,0, 0 l0 l0 CuO 0 to l0 MnO 0 to [0 ZnO 0 to 10 2x0, 0 to 5 Sb,0,0 to 5 Air, 0 to 18 P,O, 0 to 5 at least one member of the group AllandA1 0 being present in the glass batch composition.

Particularly useful glass batch compositions encompassed by the presentinvention are shown below in mole percent.

Component Mole Percent SiO not less than 70 CdO 3 to 10 A|,0, 5 lo 10rio, s l0 Still further preferred compositions of the present inventionare defined below in mole percent:

Component Mole Percent SiO, 70 to 85 CdO l to AI,O 0 to l5 TiO, 5 to lo8,0, 0 to 5 MnO 0 to 5 ZnO 0 to 8 CuO 0 to 5 P,O, 0 to 5 The followingtables contain examples that further illustrate the present inventionwithout limiting it in any way. All examples are expressed in terms ofmole percent based upon the total glass batch composition.

TABLE I were capable of being readily melted at l,600 C. in conventionalmanner in platinum or ceramic crucibles to produce a desirable glasshaving a coefficient of thermal expansion in the low-to-medium range of10 X 10" to 20 X l0"in./in./C. over the temperature range of from 0 to300 C.

The following table contains data relating the coefficient of linearthermal expansion with each of several representative glasses of theinvention.

TABLE IV In the preparation of the above examples, various size batcheswere made including samples of 100 grams in weight. Any suitable sourceof high purity raw materials can be used, and it will be readilyapparent that only minor amounts of ingredients in the nature ofimpurities can be introduced into the compositions.

The components of the glass compositions of the present invention can beintroduced in any suitable form such as but not limited to oxides,nitrates, carbonates, etc.

Melts were generally made in platinum crucibles, platinum rhodium beingwell suited for this operation. Electric furnaces were used and the meltheld for several hours to ensure homogeneity, freedom from bubbles, etc.

Although the emphasis in the foregoing examples and discussion has beenwith regard to glasses containing up to l5 mole percent CdO, the upperlimit can be extended.

qq szel ltthq les e Breast d m hssla batch Q The ranges 5f baiciforisrimemsgronh in TABLES r and II above is summarized in TABLE IIIfollowing:

TABLE III Additionally, it is important that, as will be observed fromTABLES I and II, that each example contains, in addition to the basicSi0 and CdO constituents, at least one other constituent providing anecessary amount of either boron or aluminum from which B 0 or A1 0 maybe formed in the ultimate glasses resulting from the batch compositionsof this invention. For example, in each example boron is present oraluminum is present. In the case of boron, the preferred source is B 0In the case of aluminum, the preferred sources are A1 0 AIPO, or MP Ineach instance the batch compositions of this invention positions of thepresent invention are characterized by a lowto-medium thermal expansion.The coefficient of linear thermal expansion of representative glassesranges from about l0 to about 2. X 10" (0-300 C.). However, this rangeof thermal expansion is by no means intended to be restrictive orlimiting of the compositions. Coefficients of thermal expansion bothabove and below the above values can be obtained by selection ofcomponents, and therefore such variations are intended to be encompassedby the present invention.

Among the many useful and practical applications for the glasses of thepresent invention are applications such as laboratory ware, cook ware,as well as optical instruments, and solder glasses.

It will be understood that various other modifications will be apparentto and can be readily made by those skilled in the art without departingfrom the scope and spirit of this invention.

I claim: characterized 1. A glass batch composition for producing aglass having a linear coefficient of thermal expansion within the rangeof from about 10 X 10' to 20 X 10 in./in./ C. over the range of from0300 C., and having a composition consisting essentially of 70 to molepercent SiO l to 15 mole percent CdO, and the remaining balance of saidglass batch composition consisting essentially of at least one of thefollowing constituents in the indicated ranges of mole percents:

Constituents Mole Percent rio, 0-10 A1 0, 3-10 5,0, 0-10 3"? as 9. Aglass batch composition, as defined in claim 1, wherein [Ho said SiOCdO, A1 TiO and ZnO are present in said com' position in about thefollowing mole percents: sb,o, 0-5 F1 0-18 5 Constituent Mole PercentP103 sio, 77.3 CdO 6.9 2. A glass batch composition, as defined in claim1, wherein A 2 91 said SiO CdO, A1 0 "H0 and B 0 are present in saidcom- 2% 3'; position in about the following mole percents: l0

10. A glass batch composition, as defined in claim 1, :fg 22: Perm"wherein said SiO CdO, Al O TiO and ZnO are present in l I 6 L0 saidcomposition in about the following mole percents: Al,0, 6 5 ConstituentMole Percent 4 sio 77.3 CdO 4.5 3. A glass batch composition, as definedin claim 1, wherein $16 3 said SiO CdO, A1 0 TiO and B 0 are present insaid com- 15 position in about the following mole percents: 20

11. A glass batch composition, as defined in claim 1, cfmsliwem MolePercent wherein said SiO CdO, A1 0 TiO and MnO are present in 2'36 ggsaid composition in about the following mole percents: Ago, 6.5 TiO 6.0Constituent Mole Percent n,o 4.5. sio 77.3

CdO 4.5 as 4. A glass batch composition, as defined in claim 1, whereina s 2'; said SiO CdO, Al O and "H0 are present in said composition inabout the following mole percents:

12. A glass batch composition, as defined in claim 1, Constituent MolePercent wherein said SiO CdO, A1203, Ti0 and MR0 are present in $3 3-?said composition in about the following mole percents: 0, 911 TiO 6.8Constituent Mole Percent SiO, 77.3 CdO 4.5 5. A glass batch composition,as defined in claim 1, wherein A120: said SiO CdO, M 0 and Ti0 arepresent in said com osi- Tao 4.5 tion in about the following molepercents: Mno

4Q Consume, Mule Percent 13. A glass batch composition, as defined inclaim 1, sio 7 wherein said SiO CdO, A1 0 TiO and MnO are present in 010said composition in about the following mole percents: Al o 9.1 110 9.1

Constituent Mole Percent sioI 77.3 6. A glass batch composition, asdefined in claim 1, wheretn Q10 63 said SiO CdO, A1 0 TiO and CuO arepresent in said com- A11 9.1 position in about the following molepercents: E s Constituent Mole Percent sio 77 3 14. A glass batchcomposition, as defined in claim 1, wherein said SiO CdO, A1 0 and TiOare present in said Ano, 9.r composition in about the following molepercents: no, 45 Cuo 4'5 5 Constituent Mole Percent I i sio, 77.3 85.77. A glass batch compositlon, as defined in claim 1, wherein CdO 4.8 9.1said SiO CdO, A1 0 TiO and ZnO are present in said com- #16 position inabout the following mole percents: 1

M l P 15. A glass batch composition, as defined in claim 1, g g mamwherein said SiO CdO, A1 0 and Ti0 are present in said 23 composition inabout the following mole percents: 741,0, 9.: Constituent Mole PercentZnO 2.3-6.8 773 CdO 9.1 8. A glass batch composition, as defined inclaim 1, wherein A120, 9.1 said SiO- CdO, M 0 TiO and ZnO are present insaid comosition in about the followin mole ercents: p g p 16. A glassbatch composition, as defined in claim 1, Constituent Mole Pemcm whereinsa1d S1O CdO, A1 0 and T10 are present in said Sioz 773 composition inabout the following mole percents: CdO 2.3 lg s 9.1 Constituent MolePercent T10, 4.5 85] Zno 6.8 cm 4.8

TiO, 4.8

17. A glass batch composition, as defined in claim 1, wherein said SiOCdO, ZrO M and Sb O are present in said composition in about thefollowing mole percents:

Constituent Mole SiO, 77.3 CdO 9,1 ZrO, 4.5 A50, 4.5 Sb,O, 4.5

18. A glass batch composition, as defined in claim 1, wherein said SiOCdO and A1 0 are present in said composition in about the following molepercents:

Constituent Mole Percent SiO, 81.8 CdO 9.] ALO, 9.1

19. A glass batch composition, as defined in claim 1, wherein said SiOCdO, B 0 and AIR, are present in said composition in about the followingmole percents:

Constituent Mole Percent sio, 77.3 CdO 9.! 3,0, 4.3 MP, 9.1

2. A glass batch composition, as defined in claim 1, wherein said SiOCdO, A1 0 TiO and All are present in said composition in about thefollowing mole percents:

Constituent Mole Percent sio 73.9 CdO 8.7 A1 0, 4.3 TiO, 4.3 AlF, 8.7

21. A glass batch composition, as defined in claim I, wherein said SiOCdO, TiO and AlF are present in said composition in about the followingmole percents:

Constituent Mole Percent SiO 70.8 CdO 8.3 TiO 4.2 AIF, 16.7

22. A glass batch composition for producing a glass having a linearcoefficient of thermal expansion within the range of from about X 10 toX 10' in./in./ Cover the range of from 0-300 C., said glass batchcomposition being capable of being melted at l,600 C. and having acomposition consisting essentially of 70 to mole percent SiO from 1 to15 .0 mole percent CdO, and the remaining balance of said glass batchcomposition consisting essentially of the following constituents in theindicated ranges of mole percents:

Constituents Mole Percent TiO, 5-l0 B 0, 0-4.5 ZrO, (3-4.5 AI O; 3-10AlF; O-l6.7 AIPO, 0-l0.0 CuO 0-4.5 ZnO O-6.8 MnO 0-4.5 SE50, 0-4.5

23. A glass batch composition for producing a glass having a linearcoefficient of thermal expansion within the range of from about 10 X 10to 20 X 10" in./in./ C. over the range of from O-300 C., said glassbatch composition being capable of being melted at 1,600 C., and havinga composition consisting essentially of 70 to 90 mole percent SiO,,, 1to 15 mole percentCdO and the remaininfi balance of the glass batchcomposition consisting of the f0 owing constituents in the indicatedrange of mole percent:

24. A glass batch composition for producing a glass as defined in claim28 wherein said glass batch composition consists essentially of 70 to 90mole percent SiO from 3.0 to 10.0 mole percent CdO and the remainingbalance of said glass batch composition consists essentially of thefollowing con stituents in the indicated ranges of mole percent:

Constituents Mole Percent AI,O; 5-10 TiO, 5- l 0 B 0, 4-5 ZrO, 0-5 AIF,0-1 8 CuO 0] 0 ZnO 0- l O MnO 0- l 0 Sb=O 0-5 no, 0-5

(5/69) UNITED STATES PATENT oTTTtT ,QER'NHEATE 0F 0RREUHN Patent No.3,650,781 Dated March 2] 1972 Invent r s NILS TRYGGVE E.A. BAAK It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Abstract, Col. 2, line 5, after "up delete "l" Abstract, Col. 2, line 6,"Composition" should be composition-' Col. 1, line 4, after "1965"insert -and; Col. 1, line 51, after "vat-which" should be which at--Col. 4, line 49, "2 should be '20---' Col. 7, claim "2" should beclaim--'-20-* Col. 8, claim 24, line 2, 28" should be 23--.

Signed and sealed this 10th day of April 1973 (SEAL) Attest:

EDWARDJLPLETCHERJR. ROBERT GOTTSCHALK Attesti'ng Officer Commissioner ofPatents

2. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and B2O3 are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 82.0 CdO 1.0 Al2O3 6.5 TiO2 6.0 B2O3 4.5
 2. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and AlF3 are present in said composition in about the following mole percents: ConstituentMole PercentSiO2 73.9 CdO 8.7 Al2O3 4.3TiO2 4.3 AlF3 8.7
 3. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and B2O3 are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 80.0 CdO 3.0 Al2O3 6.5 TiO2 6.0 B2O3 4.5.
 4. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3 and TiO2 are present in said composition in about the following mole percents: Constituent Mole PercentSiO2 75.0 CdO 9.1 Al2O3 9.1 TiO2 6.8
 5. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3 and TiO2 are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 72.7CdO 9.1 Al2O3 9.1 TiO2 9.1
 6. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and CuO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 4.5 Al2O3 9.1 TiO2 4.5 CuO 4.5
 7. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and ZnO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 2.3 - 6.9 Al2O3 9.1 TiO2 4.4 - 4.5 ZnO 2.3 - 6.8
 8. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and ZnO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 2.3 Al2O3 9.1 TiO2 4.5 Zno 6.8
 9. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and ZnO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 6.9 Al2O3 9.1 TiO2 4.4 ZnO 2.3
 10. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and ZnO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 4.5 Al2O3 9.1 TiO2 4.5 ZnO 4.5
 11. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and MnO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 4.5 - 6.8 Al2O3 9.1 TiO2 4.5 MnO 2.3 - 4.5
 12. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and MnO are present in sAid composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 4.5 Al2O3 9.1 TiO2 4.5 MnO 4.5
 13. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3, TiO2 and MnO are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 6.8 Al2O3 9.1 TiO2 4.5 MnO 2.3
 14. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3 and TiO2 are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 - 85.7 CdO 4.8 - 9.1 Al2O3 4.8 - 9.1 TiO2 4.5 - 4.8
 15. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3 and TiO2 are present in said composition in about the following mole percents: ConstituentMole PercentSiO2 77.3 CdO 9.1 Al2O3 9.1 TiO2 4.5
 16. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, Al2O3 and TiO2 are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 85.7 CdO 4.8 Al2O3 4.8 TiO2 4.8
 17. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, ZrO2, Al2O3 and Sb2O3 are present in said composition in about the following mole percents: Constituent Mole SiO2 77.3CdO 9.1 ZrO2 4.5 Al2O3 4.5 Sb2O3 4.5
 18. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO and Al2O3 are present in said composition in about the following mole percents: ConstituentMole PercentSiO2 81.8 CdO 9.1 Al2O3 9.1
 19. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, B2O3 and AlF3 are present in said composition in about the following mole percents: Constituent Mole Percent SiO2 77.3 CdO 9.1 B2O3 4.3 AlF3 9.1
 21. A glass batch composition, as defined in claim 1, wherein said SiO2, CdO, TiO2 and AlF3 are present in said composition in about the following mole percents: Constituent Mole PercentSiO2 70.8 CdO 8.3TiO2 4.2AlF3 16.7
 22. A glass batch composition for producing a glass having a linear coefficient of thermal expansion within the range of from about 10 X 10 7 to 20 X 10 7 in./in./* C. over the range of from O*-300* C., said glass batch composition being capable of being melted at 1,600* C. and having a composition consisting essentially of 70 to 90 mole percent SiO2, from 1 to 15.0 mole percent CdO, and the remaining balance of said glass batch composition consisting essentially of the following constituents in the indicated ranges of mole percents: Constituents Mole Percent TiO2 5-10 B2O3 0-4.5 ZrO2 0-4.5 Al2O3 3-10 AlF3 0-16.7 AlPO4 0-10.0 CuO 0-4.5 ZnO 0-6.8 MnO 0-4.5 Sb2O3 0-4.5
 23. A glass batch composition for producing a glass having a linear coefficient of thermal expansion within the range of from about 10 X 10 7 to 20 X 10 7 in./in./* C. over the range of from 0*-300* C., said glass batch composition being capable of being melted at 1,600* C., and having a composition consisting essentially of 70 to 90 mole percent SiO2, 1 to 15 mole percent CdO and the remaining balance of the glass batch composition consisting of the following constituents in the indicated range of mole percent: Constituents Mole Percent TiO2 5-10 Al2O3 3-10 B2O3 0-10 CuO 0-10 MnO 0-10 ZnO 0-10 ZrO2 0-5 Sb2O3 0-5 AlF3 0-18 P2O5 0-5
 24. A glass batch composition for producing a glass as defined in claim 28 wherein said glass batch composition consists essentially of 70 to 90 mole percent SiO2, from 3.0 to 10.0 mole percent CdO and the remaining balance of said glass batch composition consists essentially of the following constituents in the indicated ranges of mole percent: Constituents Mole Percent Al2O3 5-10 TiO2 5-10 B2O3 4-5 ZrO2 0-5 AlF3 0-18 CuO 0-10 ZnO 0-10 MnO 0-10 Sb2O3 0-5 P2O5 0-5 